April 2, 1999
Fresh Source Of 'Nursery' Cells Found In Blood
By Maggie Fox, Health and Science Correspondent
WASHINGTON (Reuters) - Researchers said Thursday they had found a fresh
source of stem cells -- the so-called nursery cells that can give rise
to all other kinds of cells -- in the bone marrow.
The team at tiny biotech company Osiris Therapeutics in Baltimore,
Maryland said they had coaxed stem cells from human bone marrow into
growing into fat, cartilage and bone tissue.
They said the technology offers new ways to treat bone cancer, tendon
damage and conditions such as AIDS-related wasting.
``This is another stem cell that can be isolated from adults that gives
rise to multiple tissues in the body,'' cell biologist Mark Pittenger,
who led the study, said in a telephone interview.
There are two kinds of stem cells. Embryonic stem cells, found, as the
name implies, in very early embryos, have the potential to become a
complete animal.
Osiris worked with another kind of stem cell, one found in tiny amounts
throughout the body, which give rise to different kinds of cells that
can become virtually any kind of cell, but which do not seem to have the
potential to develop into a complete organism.
Adults keep a few of these cells in their body, probably for repair
after accidents or disease. There are so few that scientists wanting to
use them have to find the cells and then grow them into large enough
numbers to use.
Such stem cells are often taken from bone marrow for regenerating the
immune system, for instance, after cancer therapy, or for treating
childhood blood diseases.
But scientists hope stem cells can be used to grow a range of tissues,
from brain tissue to treat diseases such as PARKINSON'S, in which brain
cells are destroyed, to juvenile diabetes, in which key cells in the
pancreas die off.
The Osiris team took bone marrow stem cells, called mesenchymal stem
cells, from volunteers and tried a variety of ways to make them grow.
``The cells do respond to their environment,'' Pittenger said. ``They
respond to growth factors and growth conditions.''
When one growth factor is added, they get bone cells, Another compound
causes the cells to give rise to cartilage cells, Pittenger said.
``The cells are grown as a micromass or pellet culture,'' he said. ``We
spin the cells down in a centrifuge tube. The cells then form a ball of
cells.''
They added a growth factor known as TGF-beta and another compound known
as a glucocorticoid. So long as no blood serum was present, the cells
grew into a ball of cartilage cells.
The company has patented several of these techniques. Writing in
Friday's edition of the journal Science, they describe how they got fat
cells.
The company hopes to use fat cells to help treat people who have lost
large amounts of weight due to cancer or AIDS therapy for instance. The
cartilage cells have been tested for treating tendon injuries, while the
bone cells are being tested for use in repairing bone.
``If you have an osteosarcoma (bone cancer) and a piece of your bone is
removed, that doesn't re-generate well,'' Pittenger said. But the
company hopes to take a patient's own stem cells, turn them into
bone-producing cells, grow them on a matrix and insert this into the
hole.
Tests on animals show this has worked, the company said. They have also
tested their cartilage cells in repairing torn tendons. ``I think that
the potential here is great,'' Pittenger said.
Osiris, which estimates the market for adult stem cell technology will
be worth $20 billion worldwide a year, has a web site describing the
technology at www.osiristx.com.
Copyright © 1999 Reuters Limited.
--
Judith Richards, London, Ontario, Canada
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